At least you can be comforted by the fact that your tank's name indicates he has read the super-sweet series of novels by Stephen Erikson. Although, I had trouble understanding why a mage would have 46k health...

DBM tells you about impale over a second before it hits. A disc priest could have tossed a shield and pain suppression. A holy priest could have cast Guardian spirit. Pom would have skimmed a bit of that first hit aswell. All healers could have chosen a different cast when they noticed the impale comming up, all in all this was just bad luck i think, one heal landing only half a second later would have changed that situation. All things you can do about it rely on knowing when an impale will hit though. If you get an unlucky combo you'll see the tank drop like that. No way to respond with reactive healing unless trough pure luck.

I disagree with the "CD rotation" comment. This is not the right tactic.Since Impale hits so hard you should have dedicated rogues who should be worrying about keeping him disarmed all the time. No weapon - no Impale - no crazy damage.

Looking at the damage number in the Recount pic , that's a pretty crazy number. Assuming your tank mitigated 60% of the original blow, that would have placed the incoming damage at 92k. 105k if your tank mitigation is at 65% - Ouch!

I know my guild managed to take Gormok down a week ago (but wiped on the worms) but I wasn't there so I don't know what kind of damage our tanks were taking and there is no combat log parse. Should be interesting to look at WMO or a similar site at parses of other Gormok fights to see the numbers other guilds are seeing.

I believe that disarm doesn't work in Heroic. My guess is they were working on Heroic, as we had many similar tank deaths when we tried it. We were seeing similar kinds of damage even switching at 2 stacks.

In H-ToC-25, we run it with three tanks switching each two stacks. As I am merely doing damage, I don't listen much but I am hearing holy priests wings being tossed as well as divine protection for the worm tanks when they are done.

Here is our WoL (on damage taken of all our 14 attempts): http://www.worldoflogs.com/reports/k6MeaguGy98rHiOs/sum/damageTaken/?enc=bosses&boss=34796

For our guild, we use 2 tanks. Each of them eat 4 stacks and we just heal through it. I'll usually Sacred Shield the first tank, then myself when I tank the boss, to try to soften the blow a little bit.

This is why I feel for the healers. Back when ulduar was "pre nerf" I saw all the damage, and kept thinking, how the hell are they doing it?

Good lord, when is healing going to go from "throw all the damage you can everywhere, including the tanks" to something more fun? I have dual spec holy set, and I pretty much only heal heroics and the occasional naxx run. I don't know how my ulduar healers do it, honestly.